This invention relates to a hand operated fence wire tensioning tool which can be used with all types of fence wire and in association with a variety of different size and types of fence post.
A number of different fence wire tensioning devices exist but these usually rely upon a separate linkage to a straining post or second fixed anchor point, whilst operating with serrated jaws to achieve a gripping effect. Such devices are often heavy, cumbersome in operation, time consuming to set up and usexe2x80x94and they invariably damage the plastic coating or metal plating that is applied to the fence wire to prevent rusting and deterioration.
A wire tensioning device is disclosed in GB-A-2185080 comprising a head for engaging a post to which wire is to be attached and an elongate lever member. The head is pivotally connected to the lever member. The head and lever member having surfaces which define a reducible area for receiving the wire. The lever is lent on to trap the wire in the reducible area and to tension the wire about the post.
A problem encountered with such prior art tools is that the head is formed with a curved and pointed surface for engaging a post. As the wire is stretched the head either slides round the post or, the head pivots on a progressively smaller point of contact. Thus as the tension in the wire increases the tool becomes progressively more unstable as the head moves away from the post.
An object of this invention is to provide a simple and effective means of tensioning fence wires before stapling in the usual wayxe2x80x94especially when an operative is working alone and without mechanical aids such as a tractor, ratchet device or pulley system; or more particularly when working in a restricted, sloping or uneven working position where such devices may be difficult or unsafe to operate. It is a further object to overcome the aforementioned problem with the prior art.
Accordingly the invention provides a fence wire tensioning tool comprising a pivoting foot for engaging a fence post, a handle member including a first jaw surface, the handle member being pivotally attached to an intermediate arm member carrying a second jaw surface opposing said first jaw surface to provide jaws for gripping a fence wire, the pivoting foot member being pivotally attached to said intermediate arm member, whereby when the jaws are closed on a wire the intermediate arm member and the handle provide a lever pivoting about the pivot point of the pivoting foot. The foot bearing on a fence post provides a constant bearing surface so that the stability of the tool is improved as the amount of tension applied to the wire increases.
The pivoting foot may have an arcuate bearing surface. The bearing surface may be serrated, ribbed, denticulate or covered with a friction type material. The gripping section may be made of Durbar (RTM) or similar sheet or plate material which offers a pre-formed surface texture. The radius of the bearing surface is dependent on the size of fence post on which it is intended to be used. The bearing surface radius may be in the range 40 to 100, preferably 60 to 80 mm. The bearing surface radius may be 75 mm.
The leverage applied to the handle effects a class 2 lever acting against the pivot point of the positioning foot. Simultaneously, a double class 1 lever action is effected on the wire held between the jaws. The arrangement allows a single handed action.
The wire is gripped by said jaws, which may engage by means of an eccentric cam action. This arrangement reduces the damage to the surface of the wire as the force on the wire is distributed evenly across the jaws to reduce the risk of the wire being cut or distorted by point contact and preventing slippage.
Each of said intermediate arm member and said handle may include pairs of said first and second opposing jaw surfaces. The jaws on both sides of the tool allow both left handed and right handed operation of the tool.
The wire tensioning tool may comprise a resilient means associated with the handle and acting against the leverage applied to the handle. The resilient means may conveniently be a compression spring. It has been found that the presence of the resilient means assists in opening the jaws once a wire has been put in place.
The handle may be provided with a rubber or plastic friction handgrip. The handle may be attached to a jaw assembly by swaging. Alternatively the handle is attached by means of welding, brazing, a screw thread, rivets, socket or force fit to. spigot.
The wire tensioning tool may be made from metal, plastics material, rubber, or from a combination of these and other suitable materials. Preferably the fence wire tensioning tool is made out of metal but certain parts of it may instead be constructed from modem materials such as carbon fibre or certain plastics, which offer advantages for ease of manufacture or weight reduction without compromising the necessary leverage required to operate successfully.
A fence wire tensioning tool including a handle and fixed and movable jaws and a pivoting foot or other similar device which can be positioned against or effect a means to engage a fence post for the purpose of tensioning fence wires prior to stapling in the usual way is provided.
The tool of the invention may be advantageously used for all purposes where it is desired to tension wires and may be particularly useful in the agricultural, horticultural and construction industries. The tool may also be sold via the DIY trade.